T1 L11 Coeliac disease & IBD Flashcards Preview

Module 104 - Nutrition, metabolism & excretion > T1 L11 Coeliac disease & IBD > Flashcards

Flashcards in T1 L11 Coeliac disease & IBD Deck (35)
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1
Q

What is coeliac disease?

A

A gluten sensitive enteropathy or coeliac sprue
Autoimmune mediated disease of the small intestine that is triggered by the ingestion of glucose which leads to malabsorption

2
Q

What is gluten?

A

Protein component of wheat, rye and barley which is left behind after washing off starch
Consists of gliadin & glutenin

3
Q

There is a high prevalence of coeliac disease in what groups of patients?

A

Down’s syndrome
Type I diabetes mellitus
Auto-immune hepatitis
Thyroid gland abnormalities

4
Q

What is the mechanism for coeliac disease?

A

1) Gluten in wheat plus small bowel mucosa
2) Tissue transglutaminase produced
3) Diamidates glutamine in gliadin
4) Negatively charged protein
5) IL-15
6) Natural killer cells & intraepithelial T lymphocytes
7) Tissue destruction & villous atrophy

5
Q

How does coeliac disease present?

A

The hallmark is the malabsorption of nutrients
Short stature & failure to thrive in children
Diarrhoea & steatorrhoea
Weight loss & fatigue
Anaemia
Osteopenia & osteoporosis

6
Q

What are the classifications of coeliac disease?

A

Classical - malabsorption symptoms
Non-classical including symptoms outside GI tract
Subclinical - detected with blood tests

7
Q

What symptoms are there for non-classical coeliac disease?

A
Constipation, bloating, alternate bowel habits
Heartburn
Nausea
Vomiting
Dyspepsia
Recurrent miscarriages / infertility
8
Q

What investigations are done for coeliac disease?

A

General investigations - FBC, urea & electrolytes, LFT
Serology for diagnosis
HLA DQ2 & HLA DQ8 in children with positive TTGA & symptoms to avoid doing a biopsy
Duodenal biopsies

9
Q

What does serology look for in coeliac disease?

A

Tissue transglutaminase IgA (TTGA)
Endomysial IgA - connective tissue covering smooth muscle fibres
Deamidated gliadin peptide IgA & IgG
Also used to monitor adherence to gluten free diet
Sero-negative coeliac disease reported

10
Q

What routine coeliac disease tests are carried out?

A

Tissue damage tests
When the small bowel is exposed to gluten there is an overreaction of the immune system to produce antibodies to proteins involved in the tissue damage: tissue transglutaminase, endomysium, deaminated gliadin peptide

11
Q

What are the microscopic features of coeliac disease?

A

At least 4 biopsies have to be sampled from the duodenum via an upper GI endoscopy as the changes can be patchy

Villous atrophy
Crypt hyperplasia
Increase in lymphocytes in lamina propria / chronic inflammation
Increase in intraepithelial lymphocytes
Recovery of villous abnormality on a gluten-free diet

12
Q

What are the complications associated with coeliac disease?

A

Enteropathy associated T cell lymphoma
High risk of adenocarcinoma of the small bowel & other organs such as large bowel, oesophagus, pancreas
May be associated with dermatitis herpetiformis
Infertility & miscarriage
Refractory coeliac disease despite strict adherence to gluten free diet

13
Q

What does inflammatory bowel disease constitute?

A
Crohn's disease
Ulcerative colitis
Diverticular disease
Ischaemic colitis
Drug-induced colitis
Infective colitis
14
Q

What is Crohn’s disease?

A

Idiopathic, chronic inflammatory bowel disease that is often complicated by fibrosis & obstructive symptoms.
It can affect any part of the GI tract from the mouth to the anus

15
Q

What is the cause of Crohn’s disease?

A
Exact causes are unknown
Genetic
Infectious
Immunologic
Environmental
Dietary
Vascular
Smoking 
NSAIDs
Psychological factors
Defects in mucosal barrier
16
Q

What are the genetics of Crohn’s disease?

A

Evidence for a genetic predisposition
No classical mendelian inheritance but it is polygenic
NOD2

17
Q

What is NOD2?

A

Nucleotide binding domain
Also known as IBD1 gene on chromosome 16
Encodes a protein that binds to intercellular bacterial peptidoglycans to activate nuclear factor kappa B. This inhibits the normal immune response to luminal microbes leading to uncontrolled inflammation

18
Q

What is the infectious cause of Crohn’s disease?

A

Granulomas present in 60-65% of patients
Mycobacterium paratuberculosis extensively investigated
Other infectious organisms: measles virus, pseudomonas, listeria

19
Q

What are the environmental factors that may cause Crohn’s disease?

A

Improved hygiene hypothesis
Reduces enteric infections & reduces ability of GI tract mucosa to develop regulatory processes that normally limit immune response to pathogens which cause self-limiting infections
Migration from a low to high risk population increases risk
Smoking doubles risk

20
Q

What are the clinical features of Crohn’s disease?

A

Chronic, indolent course punctuated by periods of remission & relapses
Abdominal pain relieved by opening bowels
Prolonged, non-bloody diarrhoea
Blood may be present if colon is involved
Loss of weight, low grade fever

21
Q

What is the distribution of Crohn’s disease?

A

Any part of GI tract from mouth to anus
Small bowel only - 40%
Large bowel only - 30%
Small & large bowel - 30%

22
Q

What are the morphological features of Crohn’s disease?

A

Fat wrapping of serosa
Typically segmented morphology
Ulceration with cobblestone pattern
Strictures due to fibrosis

23
Q

What is the microscopic appearance of Crohn’s disease?

A
Transmural or full thickness inflammation of bowel wall
Mixed acute & chronic inflammation
Preserved crypt architecture
Mucosal ulceration
Fissuring ulcers
Granulomas
Fibrosis of the wall
24
Q

What are the complications of Crohn’s disease?

A
Intra-abdominal abscesses
Deep ulcers lead to fistula
Sinus tract
Obstruction due to adhesion
Obstruction due to strictures caused by increased fibrosis
Perianal fistula & sinuses
Risk of adenocarcinoma
25
Q

What is ulcerative colitis?

A

Chronic inflammatory bowel disease that only affects large bowel from rectum to caecum
Inflammatory process is confined to mucosa & submucosa except in severe cases

26
Q

What is the cause of ulcerative colitis?

A

Cause is unknown
Multiple factors are implicated
Genetics are not as well defined

27
Q

What are the environmental factors of UC?

A

Smoking is protective
NSAID exacerbate UC
Antioxidants vitamin A & E found in low levels

28
Q

What are the clinical features of UC?

A
Intermittent attacks of bloody diarrhoea
Mucoid diarrhoea
Abdominal pain
Low grade fever
Weight loss
29
Q

What are the macroscopic features of UC?

A

Affects large bowel from rectum to caecum
Can affect rectum only (proctitis), left side (splenic flexure to rectum) or whole large bowel (total colitis)
No ulcers on endoscopic examination in early disease
Diffuse mucosal involvement which appears haemorrhagic
In chronic case the mucosa becomes flat with shortening of the bowel

30
Q

What are the microscopic features of UC?

A

Inflammation confined to mucosa
Diffuse mixed acute & chronic inflammation
Crypt architecture distortion
In inactive UC the mucosa may be atrophic with little or few inflammatory cells in lamina propria

31
Q

What are the complications of UC?

A
Leads to surgery
Refractory to medical treatment
Toxic megacolon 
Refractory bleeding
Dysplasia or adenocarcinoma
32
Q

What is toxic megacolon?

A

Bowel is grossly dilated & haemorrhage
Patient is very ill
Bloody diarrhoea
Abdominal distention
Electrolyte imbalance with hypoproteinaemia

33
Q

What are the extra-intestinal manifestations of CD & UC?

A

Ocular - uveitis, iritis, episcleritis
Cutaneous - erythema nodosum, pyoderma gangrenosum
Arthropathies - ankylosing spondylitis
Hepatic - screlosing cholangitis

34
Q

What investigations are done in UC?

A

FBC
Urea & electrolytes
Liver function tests
Inflammatory markers - C reactive protein
Endoscopy & biopsies
Radiological imaging - barium studies, MRI, U/S, CT

35
Q

Why is it important to differentiate CD from UC?

A

A patient may have a pouch after surgery in UC but not in CD because of the risk of recurrence
A pouch is created from the small bowel as stool reservoir following removal of large bowel.